001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *  
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *  
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License. 
018 *  
019 */
020package org.apache.directory.server.kerberos.shared.crypto.encryption;
021
022
023import java.security.NoSuchAlgorithmException;
024import java.util.Collections;
025import java.util.EnumMap;
026import java.util.HashMap;
027import java.util.Map;
028import java.util.Set;
029
030import javax.crypto.KeyGenerator;
031import javax.crypto.SecretKey;
032
033import org.apache.directory.server.i18n.I18n;
034import org.apache.directory.shared.kerberos.codec.types.EncryptionType;
035import org.apache.directory.shared.kerberos.components.EncryptionKey;
036import org.apache.directory.shared.kerberos.exceptions.ErrorType;
037import org.apache.directory.shared.kerberos.exceptions.KerberosException;
038
039
040/**
041 * A factory class for producing random keys, suitable for use as session keys.  For a
042 * list of desired cipher types, Kerberos random-to-key functions are used to derive
043 * keys for DES-, DES3-, AES-, and RC4-based encryption types.
044 *
045 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
046 */
047public class RandomKeyFactory
048{
049    /** A map of default encryption types mapped to cipher names. */
050    private static final Map<EncryptionType, String> DEFAULT_CIPHERS;
051
052    static
053    {
054        EnumMap<EncryptionType, String> map = new EnumMap<>( EncryptionType.class );
055
056        map.put( EncryptionType.DES_CBC_MD5, "DES" );
057        map.put( EncryptionType.DES3_CBC_SHA1_KD, "DESede" );
058        map.put( EncryptionType.RC4_HMAC, "RC4" );
059        map.put( EncryptionType.AES128_CTS_HMAC_SHA1_96, "AES" );
060        map.put( EncryptionType.AES256_CTS_HMAC_SHA1_96, "AES" );
061
062        DEFAULT_CIPHERS = Collections.unmodifiableMap( map );
063    }
064
065
066    /**
067     * Get a map of random keys.  The default set of encryption types is used.
068     * 
069     * @return The map of random keys.
070     * @throws KerberosException 
071     */
072    public static Map<EncryptionType, EncryptionKey> getRandomKeys() throws KerberosException
073    {
074        return getRandomKeys( DEFAULT_CIPHERS.keySet() );
075    }
076
077
078    /**
079     * Get a map of random keys for a list of cipher types to derive keys for.
080     *
081     * @param ciphers The list of ciphers to derive keys for.
082     * @return The list of KerberosKey's.
083     * @throws KerberosException 
084     */
085    public static Map<EncryptionType, EncryptionKey> getRandomKeys( Set<EncryptionType> ciphers )
086        throws KerberosException
087    {
088        Map<EncryptionType, EncryptionKey> map = new HashMap<>();
089
090        for ( EncryptionType encryptionType : ciphers )
091        {
092            map.put( encryptionType, getRandomKey( encryptionType ) );
093        }
094
095        return map;
096    }
097
098
099    /**
100     * Get a new random key for a given {@link EncryptionType}.
101     * 
102     * @param encryptionType 
103     * 
104     * @return The new random key.
105     * @throws KerberosException 
106     */
107    public static EncryptionKey getRandomKey( EncryptionType encryptionType ) throws KerberosException
108    {
109        String algorithm = DEFAULT_CIPHERS.get( encryptionType );
110
111        if ( algorithm == null )
112        {
113            throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, I18n.err( I18n.ERR_616,
114                encryptionType.getName() ) );
115        }
116
117        try
118        {
119            KeyGenerator keyGenerator = KeyGenerator.getInstance( algorithm );
120
121            if ( encryptionType.equals( EncryptionType.AES128_CTS_HMAC_SHA1_96 ) )
122            {
123                keyGenerator.init( 128 );
124            }
125
126            if ( encryptionType.equals( EncryptionType.AES256_CTS_HMAC_SHA1_96 ) )
127            {
128                keyGenerator.init( 256 );
129            }
130
131            SecretKey key = keyGenerator.generateKey();
132
133            byte[] keyBytes = key.getEncoded();
134
135            return new EncryptionKey( encryptionType, keyBytes );
136        }
137        catch ( NoSuchAlgorithmException nsae )
138        {
139            throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, nsae );
140        }
141    }
142}